1. Field of the Invention
The present invention relates to image processing apparatuses and methods, and programs, and more particularly, to an image processing apparatus and method, and a program that allow an interlace image into a higher-quality progressive image.
2. Description of the Related Art
When a subject moving in the vertical direction is photographed or when a subject is photographed while moving a photographing device in the vertical direction, aliasing distortion in the vertical direction (hereinafter referred to as “vertical aliasing distortion”) occurs in interlace images due to an insufficient restriction of the band in the vertical direction. As a result, the thickness of lines in the horizontal direction or the intensity of edge is changed. The vertical aliasing distortion may become more noticeable when interlace images are converted into progressive images (such conversion is hereinafter referred to as interlace-progressive (IP) conversion).
One IP conversion technique for improving the resolution of moving portions of a subject by performing motion-compensation using motion vectors is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2000-261768.
A technique for reducing cyclic distortion, such as vertical aliasing distortion, or random noise is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2004-88234. In this technique, motion-compensation is performed using a motion vector determined between a current frame and the previous frame (one frame before), and then, the pixel values of the pixels of the current frame and the previous frame are added by using a cyclic coefficient as a weight. If the cyclic coefficient is K (0≦K≦1), the pixel values of the pixels of the current frame and those of the motion-compensated image are multiplied by 1−K and K, respectively, and then, the pixel values are added. In this case, if the cyclic coefficient is excessively increased, image blur may occur in moving portions of the image due to afterimage although vertical aliasing distortion or random noise is reduced. Accordingly, in the invention disclosed in Japanese Unexamined Patent Application Publication No. 2004-88234, the cyclic coefficient is varied depending on moving components, which are differences between the current frame and the previous frame.